1. Technical Field
Embodiments of the present invention relate to an image forming apparatus such as a copier, printer, facsimile machine, a multifunctional machine having at least two functions of the copier, printer, and facsimile machine, and so forth, and a sheet adjusting device included in the image forming apparatus to adjust a position of a recording medium (i.e., a sheet) in a lateral direction perpendicular to a sheet conveyance direction, by moving the recording medium laterally.
2. Related Art
Japanese Patent Nos. JP-4614243-B2 (JP-2008-230832-A) and JP-3268329-B2 (JP-H08-108956-A) disclose image forming apparatuses employing a technique using a sheet adjusting device that can correct or adjust the position of a misaligned sheet in a lateral direction perpendicular to a sheet conveyance direction while the sheet is held between sheet conveyance rollers.
Such sheet adjusting devices generally include a moving mechanism in which a first moving unit moves a driving roller laterally and a second moving unit moves a driven roller laterally.
However, this addition of the moving mechanism to the sheet adjusting device has caused an increase in both size and cost of the image forming apparatus. The moving mechanism can be configured with a single moving unit that rotates the driving roller. In that case, however, the driven roller itself is fixed to the housing of the image forming apparatus, which restricts its movement laterally. Under this condition, when the sheet that is held between the driving roller and the driven roller is shifted laterally together with the driving roller of the moving mechanism, the fixed driven roller may prevent the sheet from moving to a target position due to sliding friction between the sheet and the driven roller.
By contrast, if the driven roller is allowed to rotate laterally with the driving roller due to the frictional resistance, the sheet held between the driving roller and the driven roller can be shifted together with the driving roller of the moving mechanism to the target position laterally.
However, when correcting the position of a sheet having low surface frictional resistance, the driven roller may not move the same amount as the sheet, which can cause misalignment of the sheet laterally due to low sliding friction with the sheet. As the image forming apparatus repeats this action, the position of the driven roller relative to the driving roller gradually shifts laterally, creating a large gap between the driving roller and the driven roller and separation from the sheet therebetween.